Energy-efficient touch panel device and related method

ABSTRACT

An energy-efficient touch panel control device includes a touch panel, a buffer memory, an interrupt initiation unit, for outputting an interrupt signal, an analog to digital conversion unit, for converting analog output voltage to digital trace data and storing the digital trace data in the buffer memory, and according to a control signal, switching an operating mode, an operation unit, generating a detecting result according to the digital trace data, switching the operating mode according to the control signal, a mode control unit, for generating the control signal according to the interrupt signal, and a host interface unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to an energy-efficient touch paneldevice and related method, and more particularly, to a touch paneldevice and related method which can consume less power and have a longstandby time.

2. Description of the Prior Art

For years, most IT products utilized traditional ways like keyboards ormouse as the standard user interfaces. After the touch panel devicesemerged as a new type of user interface, people start to enjoy it as avery convenient way to input command by selecting objects on the screen.On the other hand, as the concept of environmental protection draws moreand more attention, and as new generations of IT products appear on themarket, the concepts of “green product” gradually influence all designand manufacturing works of the IT products, which include the touchpanel device. Besides that, saving power consumption can have otherbenefits, too; for example, the standby time of the IT product can beextended, and the users need not to charge the battery of the devicevery often, so the users' convenience can be advanced.

The touch panel and related control device are mostly seen in theportable IT products. Please refer to FIG. 1. FIG. 1 illustrates aschematic diagram of a touch panel PANEL1 and a control device 12according to the prior art. The touch panel PANEL1 usually includes manytraces in the horizontal direction (X trace) and vertical direction (Ytrace), for forming the touch panel functions on the touch panel; thesetraces are used for sensing the human body∝s capacitance in order togenerate analog output voltages. Meanwhile, according to the operatingprinciples of the touch panel, different traces correspond to differentcapacitive load parameters.

When a touch event happens to the touch panel PANEL1, the analog outputvoltages of some horizontal traces as well as some vertical traces maychange according to where the touch event happened, and the controldevice 12 can detect the touch event by monitoring the analog outputvoltage of each trace. Inside FIG. 1, connected to the touch panelPANEL1, there is a control device 12, which includes an analog todigital converter 120, an operating control unit 122 and a hostinterface unit 124. The analog to digital converter 120, directlyconnected to the touch panel PANEL 1, is used for converting the analogoutput voltages into some data in digital format, and the resultingdigital data is then transferred to the operating control unit 122. Theoperating control unit 122 performs specific algorithms to process thedata to judge whether there exists a touch event. When the operatingcontrol unit 122 confirms a touch event, the host interface unit 124will output a message to a computer host HOST1 to notify the happeningof the touch event. Noticeably, since different traces in the touchpanel have different capacitive load parameters, every time the analogto digital converter 120 converts an analog output voltage, the analogto digital converter 120 needs to regulate its transfer ratio (magnitudeof amplification) based on the capacitive load parameter of thecorresponding trace, such that the influence of different capacitiveload corresponding to different trace can be erased (normalized). Bythis way, the digital data output by the analog to digital converter 120can be normalized by the analog to digital converter 120, and theoperating control unit 122 can perform data operations based on thosenormalized data.

Noteworthily, inside the control device 12, between the operatingcontrol unit 122 and the analog to digital converter 120, the capacitiveload parameters, used for regulating the transfer ratio of the analog todigital converter, are supplied by the operating control unit 122 one ata time. In other words, every time the analog to digital converter 120performs a conversion, only one corresponding capacitive load parameteris transferred from the operating control unit 122 to “update” thetransfer ratio of the analog to digital converter 120. Meanwhile, rightafter each analog to digital conversion, the digital output is directlytransferred to the operating control unit 122. Therefore, based on theoperating principles described above, the control device 12 has beenbusy on sending capacitive load parameters to and receiving data fromthe analog to digital converter 120, and could consume electric powerunnecessarily, such that the standby time of the touch panel devicecannot be reasonably extended, and user's convenience cannot beimproved, either.

SUMMARY OF THE INVENTION

It is therefore a primary objective of the claimed invention to providean energy-efficient touch panel device and related method.

The present invention discloses an energy-efficient touch panel controldevice, which comprises a touch panel comprising a plurality ofhorizontal traces and a plurality of vertical traces, corresponding to aplurality of capacitive load parameters, for generating a plurality ofanalog output voltages; a buffer memory for storing data; an interruptinitiation unit, for counting a data number of the data stored in thebuffer memory, and outputting an interrupt signal while the data numberis greater than or equal to a predefined value; an analog to digitalconversion unit, coupled to the touch panel and the buffer memory, forconverting the plurality of analog output voltages to a plurality ofdigital trace data and storing the plurality of digital trace data inthe buffer memory, and switching an operating mode according to acontrol signal; an operation unit, coupled to the buffer memory, forgenerating a detecting result according to the plurality of digitaltrace data, and switching the operating mode according to the controlsignal; a mode control unit, coupled to the interrupt initiation unit,the operation unit and the analog to digital conversion unit, forgenerating the first control signal to the analog to digital conversionunit, and the second control signal to the operation unit according tothe interrupt signal; and a host interface unit, coupled to theoperation unit, for transmitting a touch event message to a computerhost according to the detecting result.

The present invention further discloses an energy-efficient touch panelcontrol method, which comprises utilizing an analog to digitalconversion unit to transform a plurality of analog output voltages intoa plurality of digital trace data according to a plurality of capacitiveload parameters; storing the plurality of the digital trace data into abuffer memory; and controlling operating modes of the analog to digitalconversion unit and an operation unit according to a data number of thedata stored in the buffer memory.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic diagram of a touch panel and a controldevice according to the prior art.

FIG. 2 illustrates a schematic diagram of a touch panel control deviceaccording to the present invention.

FIG. 3 is a schematic diagram of a process of an embodiment of thepresent invention applies to the touch panel control device.

FIGS. 4A and 4B illustrate simplified timing diagrams while varying thememory size of the buffer memory.

DETAILED DESCRIPTION

Please refer to FIG. 2, which illustrates a schematic diagram of a touchpanel control device 20 according to the present invention. The touchpanel control device 20, connected to a touch panel PANEL2, is used fordetecting the presence of a touch event and sending the detection resultto a computer host HOST2. The touch panel control device 20 comprises abuffer memory 202, an interrupt initiation unit 204, an analog todigital conversion unit 206, an operation unit 208, a mode control unit210 and a host interface unit 212.

a. The operations of the touch panel control device 20 are described asfollows. First, the mode control unit 210 sets the analog to digitalconversion unit 206 to work in an active mode, and sets the operationunit 208 to stay in a sleep mode. The analog to digital conversion unit206 converts the analog output voltages to digital trace data byreferring the traces' capacitive load parameters, and stored in thebuffer memory 202. The buffer memory 202 supplies a memory space fortemporarily storing the digital trace data, and the interrupt initiationunit 204 is responsible for counting the number of digital trace datastored in the buffer memory 202. Besides, when the number of digitaltrace data stored in the buffer memory 202 is equal to or greater than apreset value MLEVEL, the interrupt initiation unit 204 will submit aninterrupt signal INTM, and the mode control unit 210 will generatecontrol signals, SWM1 and SWM2 according to the interrupt signal INTM.The analog to digital conversion unit 206 will switch its operating modeaccording to the control signal SWM1, and the operation unit 208 willswitch its operating mode according to the control signal SWM2.Preferably, for the present case, the control signal SWM1 switches theanalog to digital conversion unit 206 to a sleep mode, and the controlsignal SWM2 switches the operation unit 208 to an active mode, such thatthe electric power can be saved by turning the analog to digitalconversion unit 206 into an idle condition. Besides, preferably, thepreset value MLEVEL, used for setting a limit on the number of digitaltrace data in the buffer memory 202, is less than or equal to the datacapacity of the buffer memory 202.

On the other hand, the operation unit 208 reads the digital trace datain the buffer memory 202, performs algorithmic operations, and generatesa detection result. When the operation unit 208 completes thealgorithmic operation and generates a detection result, all the datastored in the buffer memory 202 should have been consumed (read) by theoperation unit 208, the mode control unit 210 can then switch theoperation mode of the switch touch panel control device 20 via thecontrol signals, SWM1 and SWM2. Preferably, for the present condition,the control signal SWM1 switches the analog to digital conversion unit206 back to work in an active mode, and the control signal SWM2 switchesthe operation unit 208 into a sleep mode; by following this procedure,the electric energy can be saved by turning the operation unit 208 intoan idle state.

As stated above, the mode control unit 210 is used for generating thecontrol signals, SWM1 and SWM2, which are used for controlling theoperation modes of the analog to digital conversion unit 206 and theoperation mode 208, respectively, such that the electric energy can besaved. Noticeably and preferably, the control signals, SWM1 and SWM2,can be implemented as a single control signal, or can be two differentcontrol signals. On the other hand, the host interface unit 212 is incharge of transferring a touch event message to the computer host HOST2.Besides that, the touch panel control device 20 includes a non-volatileprogram memory 220, which is connected to the operation unit 208, and isused for storing the software code used for the operations of theoperation unit 208 as well as the capacitive load parameters of all thetraces. Meanwhile, the touch panel control device 20 includes a loadparameter storing unit 222 directly connected to the analog to digitalconversion unit 206. Preferably, every time when the system is reset orbootstrapped, the operation unit 208 is responsible for transferringevery capacitive load parameters stored in the program memory 220 andstoring them in the load parameter storing unit 222. After that, theanalog to digital conversion unit 206 can access any of the capacitiveload parameters directly from the load parameter storing unit 222.Besides, preferably, the buffer memory 202 and the load parameterstoring unit 222 can be implemented as one single memory module, or astwo separate memory modules.

Noticeably, the touch panel control device 20 uses the buffer memory 202to store a large number of data; firstly, by temporarily storing thedigital trace data generated by the analog to digital conversion unit206 to the buffer memory 202, so that the analog to digital conversionunit 206 is not required to output the digital trace data directly tothe operation unit 208 every time an analog-to-digital conversioncompletes. Besides, every time the touch panel control device 20 isbootstrapped or reset, the operation unit 208 coordinates the transferof capacitive load parameters from the program memory 220 to the loadparameter storing unit 222. Therefore, every time the touch panelcontrol device 20 performs an analog to digital conversion, the analogto digital conversion unit 206 will not require the operation unit 208to send a corresponding capacitive load parameter; instead, the analogto digital conversion unit 206 can access the corresponding capacitiveload parameter directly from the load parameter storing unit 222.Therefore, compared with the prior art, the analog to digital conversionunit 206 can operate independently and complete the analog to digitalconversion without the assistance of the operation unit 208.

Most importantly, the touch panel control device 20 can coordinate theanalog to digital conversion unit 206 and the operation unit 208 to beoperated in an active mode or a sleep mode, such that part of theelectric power can be saved. In other words, when the number of digitaltrace data stored in the buffer memory 202 is equal to or greater thanthe preset value MLEVEL, the interrupt initiation unit 20 generates aninterrupt signal INTM, and then the mode control unit 210 can generatecontrol signals, SWM1 and SWM2, based on the interrupt signal INTM, suchthat the analog to digital conversion unit 206 enters into a sleep mode,and the operation unit 208 is being “waken up” and enters into an activemode. After the operation unit 208 reads the digital trace data storedin the buffer memory 202, and completes the algorithmic operations aboutthe detection of touch event, the mode control unit 210 wakes up theanalog to digital conversion unit 206, and makes it enter into an activemode, and makes the operation unit 208 enter into a sleep mode. Byfollowing this process, the analog to digital conversion unit 206 andthe operation unit 208 can be put into sleep mode alternatively, so partof the electric power can be saved.

To detail more about the operations of the touch panel control device20, please refer to FIG. 3, which is a schematic diagram of a process 30of an embodiment of the present invention applies to the touch panelcontrol device 20. It would have been obvious to one of ordinary skillin the art to understand that process 30 is for explaining the methodsand the benefits disclosed in the present invention, and is includingbut not limited just to this. The process 30 comprises the followingsteps:

STEP 300: Start.

STEP 302: The capacitive load parameters stored in the program memory220 are being transferred to the load parameter storing unit 222.

STEP 304: Set the value MLEVEL according to the memory size of thebuffer memory 202 and the applications.

STEP 306: Introduce the analog to digital conversion unit 206 into anactive mode according to the control signal SWM1.

STEP 308: Introduce the operation unit 208 into a sleep mode accordingto the control signal SWM2.

STEP 310: The analog to digital conversion unit 206 converts the analogoutput voltage into digital trace data according to the capacitive loadparameter, and stores the digital trace data in the buffer memory 202.

STEP 312: Judge whether the number of digital trace data stored in thebuffer memory 202 is greater than or equal to the preset value MLEVEL;if not, go back to STEP 310.

STEP 314: The interrupt initiation unit 204 generates an interruptsignal INTM.

STEP 316: The mode control unit 210 generates the control signal SWM2,wakes up the operation unit 208, and enters into the active modeaccording to the interrupt signal INTM.

STEP 318: The operation unit 208 completes reading the digital tracedata stored in the buffer memory 202, the mode control unit 210generates the control signal SWM1, and introduces the analog to digitalconversion unit 206 into a sleep mode.

STEP 320: The operation unit 208 performs algorithmic operations todetect the happening of a touch event according to the received digitaltrace data.

STEP 322: Judge whether a touch event happens; if not, go back to STEP306.

STEP 324: The host interface unit 212 transfers the detection resultabout the touch event in a format of data packet to the computer hostHOST2, and go back to STEP 306.

According to process 30, preferably, the STEP 310, 312 and 314 areperformed by the analog to digital conversion unit 206 and the interruptinitiation unit 204, and the rest of the STEPs are performed by theoperation unit 208 and the mode control unit 210. The related hardwareunits described in the process 30, and their placements, connectionrelations and corresponding functions have been disclosed as above, andwill not be detailed further.

Besides, preferably, the present invention can save more power byincreasing the memory size of the buffer memory 202. Please refer toFIGS. 4A and 4B, which illustrate the simplified timing diagrams whilevarying the memory size of the buffer memory 202. The analog to digitalconversion unit 206 and the operation unit 208 alternatively operated ina sleep mode (denoted by 0) or in an active mode (denoted by 1). FIGS.4A and 4B illustrate the operating states of the analog to digitalconversion unit 206 and the operation unit 208 when the size of thebuffer memory is L1 and L2 bytes, respectively. By comparing FIGS. 4Aand 4B, it can be observed that, when the data capacity of the buffermemory 20 expands, the operation unit 208 will stay longer in the sleepmode, since it will take more time to fill up the buffer memory 202. Inother words, if the memory size L2 is greater than the memory size L1,the time interval T3 will be greater than the time interval T1. Besides,since the time interval T2 is approximately equal to the time intervalT4, expanding the memory size of the buffer memory 202 can make theoperation unit 208 stays in the sleep mode at a greater proportion oftime, and then more electric power can be saved. Noticeably, when thetime difference between two “wake-ups” of the operation unit 208 hasbeen lengthened, some users may sense the response time of the touchpanel control device 20 increased, or the sensitivity decreased.Therefore, the designer is required to find an optimal value for thememory size of the buffer memory 202 by considering the system cost andthe sensitivity of the touch panel control device 20.

Noticeably, the present invention can apply a simple hardware module(not shown in the figures), which is specifically used for monitoringthe data converted by the analog to digital conversion unit 206, suchthat the converted data can be checked first to see whether anymeaningful message is immersed in the data. Next, only the data withmeaningful message and its associated trace position information aretransferred to the buffer memory 202. In this case, the operation unit208 can spend more time to stay in the sleep mode, and the powerconsumption can be lowered further by adding this hardware function.After all, the operation unit 208 can be waken up and come back in theactive mode, and can process only the data with meaningful messages.

According to the experimental results, for the control device 12 of theprior art, the analog to digital converter 120 and the operating controlunit 122 are the two most power consuming modules; between them, theoperating control unit 122 consumes even more. This is understandablebecause the operating control module 120 needs to perform the dataprocessing tasks, and to supply the analog to digital converter 120 withcharacteristic data (capacitive load parameter) of the correspondingtrace, and then to receive the digital data output by the analog todigital converter 120 after every analog to digital conversion; allthese have to be done in real time, and therefore consume more power. Inthe prior art, since the analog to digital converter 120 and theoperating control unit 122 are operative in the active mode all thetime, the power efficiency is therefore relatively poor. In comparison,the average power consumed by the touch panel control device 20 of thepresent invention is measured and accounts for about 30%-50% of powerconsumed by the control device 12 of the prior art; this is equally tosay that the standby time of the present invention is about 2 to 3 timeslonger than that of the prior art—the advantage in power saving by thepresent invention is therefore obvious.

Briefly speaking, according to the present invention, the touch panelcontrol method and device comprises a buffer memory, which is connectedbetween the analog to digital conversion unit and the operation unit,for data buffering. Also, according to the present invention, the touchpanel control method and device comprises a load parameter storing unit,such that the analog to digital conversion unit can access thecapacitive load parameters directly from the load parameter storingunit. The present invention also utilizes a mode control unit to orderlymake the operation unit and the analog to digital conversion unitsettled in a sleep mode, such that the electric power can be saved andthe efficiency can be improved.

To make a summary, according to the present invention, the touch panelcontrol device improves the overall efficiency of the touch panel deviceby utilizing a novel touch panel control method and device architecture.Also, according to the experiment, the touch panel control method andthe device architecture disclosed by the present invention caneffectively perform the touch panel function, and reduce the powerconsumption of the touch panel device, and the consumer benefits can beadvanced by extending the standby time of the touch panel device.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention.

What is claimed is:
 1. An energy-efficient touch panel control devicecomprising: a touch panel comprising a plurality of horizontal tracesand a plurality of vertical traces, corresponding to a plurality ofcapacitive load parameters, for generating a plurality of analog outputvoltages; a buffer memory for storing digital trace data; an interruptinitiation unit, for counting a number of digital trace data stored inthe buffer memory, and outputting an interrupt signal when the number ofdigital trace data stored in the buffer memory is greater than or equalto a predefined value; an analog to digital conversion unit, coupled tothe touch panel and the buffer memory, for converting the plurality ofanalog output voltages to a plurality of digital trace data and storingthe plurality of digital trace data in the buffer memory, and switchingan operating mode according to a first control signal; an operationunit, coupled to the buffer memory, for generating a detection resultaccording to the plurality of digital trace data read from the buffermemory, and switching the operating mode according to a second controlsignal; a mode control unit, coupled to the interrupt initiation unit,the operation unit and the analog to digital conversion unit, forgenerating the first control signal for the analog to digital conversionunit, and the second control signal for the operation unit according tothe interrupt signal; and a host interface unit, coupled to theoperation unit, for transmitting a touch event message to a computerhost according to the detection result; wherein the mode control unit isutilized for generating the first and second control signals accordingto the interrupt signal such that the analog to digital conversion unitis operated in a sleep mode and the operation unit is operated in anactive mode; and wherein the mode control unit is utilized forgenerating the first and second control signals after the operating unitcompletes the generating a detection result such that the analog todigital conversion unit is operated in an active mode and the operationunit is operated in a sleep mode.
 2. The touch panel control device ofclaim 1 further comprising a load parameter storing unit, coupled to theanalog to digital conversion unit, for temporarily storing the pluralityof capacitive load parameters.
 3. The touch panel control device ofclaim 2, wherein the operation unit is further utilized for moving theplurality of capacitive load parameters to the load parameter storingunit while the touch panel control device is being bootstrapped orreset.
 4. The touch panel control device of claim 2, wherein the loadparameter storing unit and the buffer memory share the same memorymodule, or use two memory modules.
 5. The touch panel control device ofclaim 3 further comprising a program memory, coupled to the operationunit, for storing the plurality of capacitive load parameters.
 6. Thetouch panel control device of claim 5, wherein the program memory is anon-volatile memory.
 7. The touch panel control device of claim 1,wherein the predefined value is less than or equal to the memory size ofthe buffer memory.
 8. The touch panel control device of claim 1, whereinthe first control signal and the second control signal are of the samecontrol signal, or two different control signals.